MICROCHIP TC665EUNTR

The TC664/TC665 devices are PWM mode fan speed controllers with FanSense technology for use with brushless DC fans. These devices implement temperature proportional fan speed control which lowers acoustic fan noise and increases fan life. The voltage at V_IN (Pin 1) represents temperature and is typically provided by an external thermistor or voltage output temperature sensor. The PWM output (V_OUT) is adjusted between 30% and 100%, based on the voltage at V_IN. The PWM duty cycle can also be programmed via SMBus to allow fan speed control without the need for an external thermistor. If V_IN is not connected, the TC664/TC665 will start driving the fan at a default duty cycle of 39.33%.

In normal fan operation, a pulse train is present at the SENSE pin (Pin 8). The TC664/TC665 use these pulses to calculate the fan revolutions per minute (RPM). The fan RPM data is used to detect a worn out, stalled, open or unconnected fan. An RPM level below the user-programmable threshold causes the TC664/ TC665 to assert a logic low alert signal (FAULT). The default threshold value is 500 RPM. Also, if this condition occurs, FF (bit 0<0>) in the Status Register will also be set to a ‘1’.

An over-temperature condition is indicated when the voltage at V_IN exceeds 2.6 V (typical). The TC664/TC665 devices indicate this by setting OTF(bit 5<x>) in the Status Register to a '1'. The TC665 device also pulls the FAULT line low during an over-temperature condition.

The TC664/TC665 devices are available in a 10-Pin MSOP package and consume 150 μA during operation. The devices can also enter a low-power shutdown mode (5 μA, typ.) by setting the appropriate bit in the Configuration Register. The operating temperature range for these devices is -40°C to +85°C.

• Temperature Proportional Fan Speed for Reduced Acoustic Noise and Longer Fan Life
• FanSense Protects against Fan Failure and Eliminates the Need for 3-wire Fans
• Over Temperature Detection (TC665)
• Efficient PWM Fan Drive
• Provides RPM Data
• 2-Wire SMBus-Compatible Interface
• Supports Any Fan Voltage
• Software Controlled Shutdown Mode for "Green" Systems
• Supports Low Cost NTC/PTC Thermistors
• Space Saving 10-Pin MSOP Package
• Temperature Range: -40°C to +85°C

• Personal Computers & Servers
• LCD Projectors
• Datacom & Telecom Equipment
• Fan Trays
• File Servers
• Workstations
• General Purpose Fan Speed Control